1. Field of the Invention
The present invention relates to disc driving apparatuses.
2. Description of the Related Art
Disc apparatuses including disc driving apparatuses have been used, such as a disc apparatus recording and playing back an optical disc stored in a case. In the disc apparatus, a disc cartridge is first move horizontally to be stored in the cabinet of the disc apparatus the disc cartridge is then lowered to be placed so that the optical disc in the case is placed on a turntable, and then a chucking member is lowered to chuck the disc.
In a disc apparatus for recording and playing back an optical disc which is not stored in a case, an optical disc is first placed on a disc tray, the optical disc is moved horizontally to be stored in the cabinet, a turntable is raised to lift the optical disc from the disc tray, and then a chucking member is lowered perpendicularly to the optical disc from above to chuck the optical disc.
Of the above-described disc apparatuses, the former apparatus needs a mechanism which moves the disc cartridge horizontally and a mechanism which moves the cartridge vertically, making these mechanisms complicated.
The latter apparatus needs a complicated mechanism for moving up and down precisely the turntable and the chucking member to perform precise chucking of an optical disc.
In a disc apparatus, the objective lens of an optical pickup is disposed movably in the radial direction of an optical disc. Usually, the optical pickup is slidably supported at a guide shaft and is moved by a linear motor or other mechanism.
Power to such a disc apparatus may be shut down for some reason during its operation, for example, by an attempt to move the disc apparatus without knowing that it is in operation during a read operation of an optical disc. In such a case, the position of the optical pickup cannot be controlled because the power to the linear motor is turned off, and the optical pickup is left on the guide shaft in the condition in which it can slide freely.
If the disc apparatus is carried in this state, the optical pickup moves, causing damage, such as errors in the precision of optical components precisely assembled and breakage of the optical pickup or members which enable the optical pickup to move freely.
To prevent such damage, the optical pickup can be driven by, for example, a rack and pinion. When the power is shut down, the motor which rotates the pinion is stopped.
With this feature, the optical pickup does not move when the power is shut down. If the optical pickup stops moving at the outer peripheral of the optical disc, however, a new problem may occur. The problem is that the optical disc is scratched when it touches the optical pickup if its outer peripheral is waved due to vibration caused in transportation of the disc apparatus.
Another problem is too long of an access time is required when the optical disc is reloaded and chucked. This is because the position of the optical pickup is not determined, as described above. To describe it precisely, when the position of the optical pickup is not determined within its movement area, the optical pickup must be moved to its reference position before signals are read from or written into the optical disc.
In some disc apparatuses, the shutter of an optical disc is closed while the disc cartridge is being loaded or after it is loaded, and the optical disc is rotated by a turntable.
In such a disc apparatus, an air flow takes place as the optical disc catches the surrounding air when it rotates. Then, air having dust enters the disc apparatus from the front slot used for loading the optical disc or other holes.
Air which enters the disc apparatus may contact an optical disc surface or an objective lens surface of the optical pickup as the above-described air flows, depositing dust on the surfaces.